I Promise
by PastelPokerChips
Summary: Magnus goes on a job to rid someone of a Greater Demon and when he comes home to Alec, he's not entirely the same. In fact, he's not Magnus at all.
1. Chapter 1

**A/N: Hey guys! I just want to let you know that if you have any fics that need beta reading, I am now accepting requests! Enjoy the story!**

* * *

Alec whistled slightly as he unlocked the door to Magnus's apartment. He turned the silver key to the left and pushed the door open.

He started scanning the room for the familiar black locks that were so often gelled into spikes.

After a quick scan that, to Alec's dismay, revealed nothing to signal that his love was here, Alec stated calling out for Magnus.

"Mags! Where are you? I'm back!"

Alec kept his calling up for a minute, but when met with no response, he decided to venture into the kitchen. It was there where he caught a glimpse of the clock that read 3:45 p.m.

Magnus wasnt due back for another hour. Alec had forgotten he had met with a customer who was facing a demon issue. A greater demon, no less.

Alex was scared to death about the possible outcomes this job had in store for his warlock. He had begged Magnus to let him tag along but he was always met with the same answer.

 _"You know, not every Downworlder fancies Shandowhunters, darling."_

He rolled his eyes when Magnus had said it then, but now he was worried about how the Magnus vs Greater Demon match would play out.

He wrung his hands ,made clammy by his worrisome thoughts, together. He could think of nothing to do to sufficiently deflect his attention off of Magnus's meeting, so he settled for the TV in Magnus's bedroom.

He would never admit it, but Magnus had definitely warmed Alec up to Project Runway b

The hour passed smoothly. Alec's thoughts, though never completely derailed, strayed from the previous path they had taken.

Alec visibly relaxed and sorted a beaming smile when he heard the door open and close, although he was upset to hear the door close with an undignified slam.

He frowned at the noise. Magnus always slammed the door when he was angry at his client, or really anything for that matter.

Alec immediately jumped up from the bed, ready to calm down the clearly upset Warlock like he had done for the past couple months.

When he entered the living room, greeted by a tense looking Magnus whose back was turned to him, he placed his hand upon the man's tense shoulder.

His back tensed further, the exact opposite of the usually reaction of relaxation to Alec's touch.

"Mags? Are you Okay?" he asked in a gentle whisper.

Magnus spun in a lightening fast motion, causing Alec to stumble back a few steps.

Alec found himself staring into the icy depth of Magnus's yellow-green eyes that were holding a harsh glare direct toward... him?

No that can't be right?

Alec carefully extended his fingers to Magnus's face, his goal to touch the man's smooth caramel skin.

Half way to its destination, the hand was smacked rather harshly, causing Alec to gasp lightly and retract his hand quickly.

Magnus's lips turned to a scowl and the emotion in his eyes melted into... disgust?

Magnus was disgusted with him?

"Ma-Magnus?" Alec stuttered out, rewarded with Magnus's snippy laughter.

Alec felt his body curl in on itself, retracting in response to his love's blatant act of humiliating him.

Magnus decided now would be the optimal time to speak up.

"You'll never do it will you?" he asked- well sneered really.

Alec recoiled further into himself.

"Do what?" he ask, scared of the answer.

Magnus snorted aloud.

"Come out, tell people about us, tell people about me." Magnus said with a shake of his head.

"We-Well I-I..." he stuttered around his words uncomfortably.

Magnus scowled once more at the slightly shorter man in front of him.

"Y-y-you'll what, Alexander?" he asked, clearly fake stuttering to make fun of Alec.

Alec's face flushed red with humiliation, confusion, and a twinge of anger, but Magnus did not stop there.

"I know what you'll do. You'll put it off and you'll say you're not ready, but the truth is you're scared. Youre too scared of mommy and daddy to tell them that hey, they're oldest son is gay. You'll hide behind you're stupid black shadow hunter gear and your ripped jeans and you're baggy sweaters for the rest of your life. And may I add that none of those things make you look even slightly appealing. You'll keep shoving me to the side and you'll keep ignoring me in front of your parents." Magnus let out a harsh laugh "I'm Magnus Bane who could have anyone he wanted in a matter of seconds and yet, here I am waiting on a closeted Shadowhunter, Shadowhunter, who blushes an ugly shade of red when anyone makes even the slightest innuendo and has pasty white skin and matted hair that looks like a dog with mange's fur."

Alec felt his eyes fill with unshed tears. He was choking on his breath now trying to hold in what he was filling.

"Please, Magnus, please stop." he whispered, begging, voice cracking embarrassingly.

Magnus scoffed at the man.

"You're crying now, really? How pathetic. That's all you are, Alec. Pathetic. Pathetic and hideous. You know, in hindsight, I'm glad you're too scared to tell your parents about us because the less people who know I dated you, a Lightwood no less, the better." he spat the name out like a cuss word.

Alec sniffled, still casting his eyes to the floor.

"Do you really think I'm hideous and pathetic, Magnus?" he needed to know this before he was thrown away by the only person he ever truly loved more than his siblings.

Magnus looked at the boy ahead of him with no remorse. "Yes, I do. Hideous, pathetic, repulsive, and everything else in between. Now put the key on the table and get out."

Alec felt the tears drop from his eyes and a sob escape his lips, but nonetheless, he still nodded.

"O-okay." he said, fishing for the key in his pocket.

When Magnus saw the tears fall and the sob leave Alec's mouth, it was like something in him snapped.

He was completely clueless as to why Alec was crying or why he was shielding his face from him.

Magnus raised his hand to try and comfort the sobbing boy.

Alec flinched at the raised hand, believing a blow to the face was next in line for him on the list of pain Magnus will inflict upon him in a single 30 minute period.

Magnus caught the flinch, and felt his own eyes water. Alec... Alec thought he would hurt him?

"Al-Alec?" Magnus said in a very out of character timid voice.

Alec didn't make a move to lift his downcast eyes dripping with tears as he shuffled toward the kitchen table and sat the key down on the wood.

Magnus may hate him but Alec still loved him. He didn't have a reason why he still felt that way even after he had all of this thrown at him.

Still looking at the floor, Alec raised his hand to wipe the tears from his dripping eyelashes.

"I'll, uh, I'll go now." Alec felt that the last goodbye warranted a look upon the warlock's face. Alec needed to take a few seconds to memorize every detail.

He looked up at Magnus through his eyelashes and Magnus looked... guilty, regretful? No, definitely not.

He took a second to prepare a little speech in his head. This had to be good if this was the last time he was to see Magnus.

He walked to the door, trying in vain to stop the water flowing from his eyes, and opened the door to the loft.

"Magnus, I-I'm sorry. I, um, I didn't know you felt that way. I'm sorry I made you go through that. So, I'll ,uh, leave now and I w-won't come back. Goodbye, Mags." his voice unceremoniously cracked several times within the course of that sentence.

Magnus was near panicked at the movements and words that Alec was authoring. Why was he leaving? Why was he crying? What did he mean 'I didn't know you felt that way'? What is happening? Watching Alec's movements he quickly pieced together what was happening. Alec was leaving and never coming back.

"Alec, Alexander, please don't do this." Magnus's voice was almost sobs as he fought to keep in the tears.

Alec shook his head. Magnus doesn't get to sound like the victim. He should be pissed beyond measure but he couldn't find it in himself to overcome the sadness that was drowning him.

He was thankful that he never worked up the courage to tell Magnus he loved him. He did love him. By the Angel, he loved him so much and he thought the feeling might be reciprocated. He was actually happy that his confession had the chance to get shot down. He didn't think he could deal with that type of rejection.

Magnus felt his eyes prick with tears. He can't lose Alec. He loved him. In fact, he hasn't loved anyone as much as he loves Alec in all of his 400 years.

Magnus tried again to get Alex to stay. He knew his time was limited and he had to say something to make Alec stay.

"Alexander, don't leave...I-I love you."

Alec felt what was left of his heart shatter. He's lying now. He feels pity for Alec. Alec felt his anger raise up at that. He didn't want Magnus's pity but he'd be lying if he said he didn't want his love.

Alec whipped around to face the caramel skinned man.

"You don't get to say that." he spat at Magnus, who in turn gave a flinch.

"You don't get to say all that crap to me and then turn around and say you love me, which might I add, it is painfully obvious that you in fact do not." Alec sighed a heartbroken sigh. He wished Magnus meant that he loved him but that didn't change anything he had said just moments before.

"You don't get to. You don't." Alec was back to his broken, cracked voice.

Magnus reached a hand up to grab Alec, make him stay, make him listen, hold on and never let go.

Alec was having none of that. He casted his eyes upon Magnus, tears unshed.

Magnus was taken aback by the utterly heartbroken look in the boy's blue eyes. What happened to Alec?

"Magnus, look, I'm sorry you've been feeling that way and I'm sorry I didn't notice earlier. You won't have to see me again, I promise."

Magnus shook his head fervently. He didn't want to never see Alec again. Frankly, he wanted to see him everyday.

A single tear dribble down Alec's cheek. "I promise." he whispered, sounding like he was talking more to himself than Magnus.

With that he left the loft, shutting the door on Magnus and leaving his heart with him. He ran. He ran all the way to the Institute not stopping for anyone.

He threw the door open with a clang and shot up the stairs, not bothering with the elevator. He knew if he stopped a break down would not be far behind.

He flung the door to his room open and flopped himself on the bed.

He clutched the pillow tight, wishing it was Magnus. Wishing Magnus was here and wishing Magnus still loved him.

* * *

Magnus stared at the door after the boy had left.

He had no idea what had hurt Alec and made him leave, but he was going to find out.

He sat on the couch staring unseeingly at the blank TV screen.

He saw the water drop on his hands before he really felt himself crying.

Soon the sobs could not longer be contained and Magnus was clutching at his chest, trying in vain to reach the pain within.

The sobs were harsh and ridged, cutting his throat with each passing noise. How was going to get Alec back?


	2. Chapter 2

Alec staggered into his room at the institute. His rage with Magnus was short-lived, fueling him only until he was standing outside of Magnus's apartment complex.

He valiantly held the tears of heartbreak in, but as he approached his bed, the dam broke and he was left with hot tears dripping down his face.

He pulled the covers of his bed back and slipped inside, silently praying that the warmth of the bed would provide the comfort as Magnus's embrace did.

Magnus.

The thought of him brought Alec back to mere moments ago when his heart was violently and viciously ripped out of his chest.

 _"Do you really think I'm hideous?"_

 _"Yes, I do. Hideous, pathetic, repulsive, and everything else in between."_

A harsh sob escaped Alec's lips despite his efforts to hold it in. He felt his lungs expand rapidly and strain against his aching ribs. Alec buried his tear-streaked face in the pillow, wishing that this was all a horrid dream and he would wake up wrapped in Magnus's arms and everything would be how it used to.

Alec would still be shy, Magnus would still be eccentric, Alec would still be gentle, and Magnus would still be sarcastic.

Alec let a sad smile creep onto his face during his remembering. He _knew_ he would never get to be with Magnus now.

Alec tried to convince himself that this was for the best. That it would have never worked anyway. That he was too shy to come out of the closet and it was better that Magnus didn't have Alec holding him back. That he was mortal and Magnus wasn't so breaking up was saving everybody unnecessary heartbreak. That Magnus deserved much more and much better than anything Alec could _ever_ give him and… and that was ok.

Alec kept repeating the list in his head but at some point, he started to say it out loud. Soon, his mumbling escalated to clear words, from clear words to slight yells, and from slight yells to blatant screams, no longer saying the words at all.

Magnus would replace him. Alec wouldn't. Magnus will get overt him. Alec won't. Alec will die still loving Magnus. Magnus won't.

* * *

Isabelle could hear the heartbreaking sobs emitting from her brother's room, although she did not know why he was sobbing.

Her mind instantly drew the conclusion that a certain warlock was involved somehow. No one knew about the relationship the Warlock and Shadowhunter held except Isabelle, and it was at this time when she was thankful that she was exceptionally perceptive… that and exceptionally good at eavesdropping and snooping through Alec's phone.

She didn't know what Magnus did or why Magnus did it, but he was _definitely_ going to pay.

* * *

Magnus stayed curled up on the couch for a considerable amount of time before he accidently rolled himself off and on to the floor.

He felt himself collide with the hard wood flooring, but he was too distraught to care. All he cared about was the utterly heartbroken look Alec was sporting while he was still in his apartment. Magnus's mind flashed back to the moments leading up to Alec's departure.

His fuzzy, broken mind was still in question about what Alec had meant when he got mad and yelled at him.

He didn't _say anything_ so why had Alec left and why wasn't he coming back?

Magnus wasn't born yesterday or even in this lifetime for that matter, so he knew that when Alec said his goodbye it wasn't a 'goodbye until tomorrow' it was a 'goodbye forever' type of deal.

The mere thought of Alec leaving forever shook Magnus to the very core of his soul. He shivered unpleasantly, feeling an awful headache creeping up on him due to all the sobbing he had done.

Alec. Beautiful, sweet, gentle, shy, the best thing that has ever happened to him Alec gone from Magnus's life forever. Magnus sobbed again, still keeping his place on the hard flooring.

Magnus thought ahead. Alec would find someone new, Magnus wouldn't. Alec will love someone else, Magnus won't. Alec will die loving another, Magnus won't.

Hell, Magnus won't even _die_ he'll never escape the heartbreak, damned to live the rest of his immortal life unloved and filled with guilt, regret, loss, and crippling heartache.

Magnus's sobs filled the room, well the whole building really, and he couldn't do anything to stop it. He was drowning in his sorrow, too tired and sad to care how loud and disturbing his sobbing was.

* * *

Isabelle waltzed up the stairs leading to the loft. She didn't know which room belonged to the warlock, but she decided she would follow the sound of complete and utter stupidity and go from there.

Isabelle Lightwood was no genius but she guess the sound of complete and utter stupidity was really similar to that of sobbing.

She approached the door of the room where the sound was coming from and banged on the door.

"BANE, WHAT IN ANGEL'S NAME HAVE YOU DONE TO MY BROTHER?" she yelled, letting her rage slip into her voice.

She was awarded with louder sobs and yells. So this was Magnus's room. Maybe she was a genius after all.

"BANE OPEN THIS DAMN DOOR!" Isabelle screamed at the top of her lungs, still banging on the door.

The sobbing did not falter for a single second. Isabelle sighed wearily while looking at her freshly manicured nails.

She backed up a few feet and readied herself. She let the electrum whip-bracelet she kept on slide down her arm.

She pulled it back and flung it, letting it snap at the doorknob, effectively breaking the door. She dusted off the nonexistent dust from her shoulders.

She was shocked, however, when she was met with a sobbing, screaming warlock laying on the floor in a haze.

She stopped just short of the couch and crouched down next to Magnus.

She just sat there for a moment, watching, listening, waiting.

As she listened closer to the distraught man, she could hear her brother's name escape his lips in broken whispers.

"Alec…Alec…. _Alexander_." the name was repeated like a prayer, and for Magnus, Isabelle figured, it was. The name, broken in weird places due to the occasional sob, was seeping past the lips of the warlock almost unconsciously.

Isabelle reached her hand out to touch the warlock, a move she mulled over quite a bit before carrying it out.

As her hand came to rest on his shoulder, Magnus flinched back rather violently and sucked in breath as if hoping that when he opened his eyes someone, someone who did not hold the name Isabelle Lightwood, would be standing there.

As he opened his eyes, Isabelle saw the exact moment when his hope was shattered. The light practically dripped out of his eyes, taking the last bit of his soul with it. Isabelle's heart felt cracked, a feeling she had not felt many times before.

She shook her head to rid herself of her thoughts. No matter how "broken" Magnus looked, he still did something to Alec and Isabelle was determined to find out what that _something_ was.

She shook the warlock, who had returned to his endless rounds of sobbing, and watched as he painstakingly pried his eyes open to reveal puffy, swollen yellow cat eyes.

Yellow cat eyes that Alec raved about when he thought no one was listening. One look into the utterly shattered eyes of the warlock, and Isabelle knew that something was wrong.

"By the Angel, Magnus, what happened?" it was a simple question, Isabelle thought, ask it get an answer. Cut and dry. Magnus, however, did not follow Isabelle's train of thought as he burst out into yet _another_ harsh round of sobbing.

He opened and closed his mouth like a fish, trying to form words. Isabelle asked what happened but that's just the thing, _he didn't know_.

"I-I d-d-don't… _Alec_." His sentence turned into a pathetic whine for his love, and Magnus knew that if he was in his right state of mind, he would be caught dead whining like he just did.

Isabelle understood despite Magnus's communication- or lack thereof- what he had meant.

She rubbed soothing circles on his shoulder, trying to comfort him even though she had almost no experience in the act.

Magnus clutched onto the wrist she wasn't using to tub circles with. He looked into her eyes, pleading, _begging_.

"Please, Isabelle, you have to help me. I-I can't lose him." His sobbing had died away to cries of lesser intensity, leaving Magnus with a hoarse voice and aching… well, _everything_ in its wake.

Isabelle nodded, allowing Magnus to close his obviously sore eyes.

She knew she had to help fix this. No, not because of Magnus, but because of Alec. Alec would be just as broken without Magnus as Magnus would be without Alec.

So right then, sitting next to the highly distressed Downworlder, she calculated a plan designed to bring Magnus and Alec back together and fix this awful dent in their relationship.


	3. Chapter 3

Isabelle walked into the Institute with a new sense of purpose. She was going to get her brother's happiness back, and she would do that no matter the cost.

She walked up to the door of Alec's room. She noted happily that she could no longer hear the raging sobs from outside the door.

She started knocking softly as to not startle her brother.

"Alec, come on, let me in," she knocked again.

And again.

And again.

Her knocks, along with her voice, grew frantic and hurried.

"ALEC! LET ME IN!" her breathing ragged, she turned and ran down the hall to Jace's room.

She was so scared that he'd done it again. He'd tried to kill himself _again_.

She threw the door open, not caring that she'd caught Clary and Jace in the middle of a quickly escalating make out session.

"Jace, help, it's Alec."

Jace felt his blood run cold at the sentence. He jumped out of bed, Clary in tow.

Jace started banging on the door harder than Isabelle and Clary ever thought possible.

Clary, bless her, pushed Jace out of the way seeing her was getting nowhere.

Jace was livid. He didn't care that it was Clary that pushed him away. Anyone who tried to keep him from his brother, his _parabatai_ , was going to get it.

Clary pulled out her stele, working in hurried motions to draw the ' _unlock'_ rune on the door.

She heard the click of the lock and pushed the door open.

Jace and Isabelle sprinted into the room, Jace stopping only to kiss Clary's forehead in thanks and relief.

As Isabelle entered the room, she was devastated, but not surprised, to find Alec with scars split open on the bathroom floor.

Her tears cascaded down in a torrent.

"Jace, come draw the rune! NOW!" she screamed in fear of losing he last _real_ brother.

Sure, Jace was like a brother and she loved him the way a sister loves a brother, but Alec was the only one left that shared her parents. Her _blood_.

"We can't lose another brother, Jace. We can't," her voice came broken with sobs.

Alec wasn't awake, but his blood was pouring out of his wrist in gushes.

Jace cringed at the sight, but quickly drew the _iratze_ on Alec's chest.

They waited a beat. Nothing happened.

The wounds weren't healing. The blood wasn't even slowing down.

Isabelle became frantic. 

"JACE IT'S NOT WORKING! CALL MAGNUS!"

Jace wasted no time in seeing to Isabelle's instructions.

He sent a fire message to the warlock basically demanding that he come tend to Alec _no matter what_ happened between them.

Jace looked down at his brother, feeling his eyes prick with tears for the first time in years.

He couldn't lose Alec. Not now, not ever.

He waited in silent panic for the warlock to show.

5 minutes later, Magnus came barreling down the hallway to his shadowhunter's room.

He stopped abruptly in front of the doorframe of Alec's room.

He ran to the huddle of people crouched in the floor.

"Out of the way," he tried to keep the brokenness out of his voice.

He crouched down to Alec, taking his mauled wrist in his hand.

By this time, Jace and Isabelle had, for the most part, got the cuts to stop bleeding but the amount of blood Alec already lost was alarming.

"Oh Alec…" he whispered and leaned down to kiss the sickly pale forehead of his love.

"Get him on the bed," he commanded, his voice hard.

Jace and Isabelle obeyed silently, hoisting Alec onto his small, rectangular bed.

Magnus rolled up the sleeves on the sweater he was wearing. Alec's sweater.

Magnus took in the appearance of the dying boy, feeling tears prick the back of his eyes.

He pinched the bridge of his nose and forced the tears back.

There was no time for tears. He was _going_ to save Alec.

It was either save him or join him and Magnus was dead set on the former.

"Alright, everyone out."

They all shuffled out albeit unwillingly.

He heard the door close behind him and he took this moment to sweep the black locks back out of Alec's eyes.

He leaned down and kissed the boy's cheek, feeling the tears return.

"I'll save you Alec, I swear."


End file.
